Isolation and structure determination of the new and novel active constituents from the extracts of Brucea javanica, Elephantopus tomentosus, Elephantopus nudatus, Wedelia chinensis, Semecarpus gigantifolia, Hyptis capitata, Wikstroemia indica and Vanilla griffithii which demonstrated significant in vivo antitumor activities in Walker 256 carcinosarcoma, P-388 lymphocytic leukemia as well as Ehrlich ascites carcinoma are currently in progress. BIBLIOGRAPHIC REFERENCES: K. H. Lee, Y. Imakura and D. Sims, "Antitumor 17: The Structure and Stereochemistry of Microhelenin-A, a New Antitumor Sesquiterpene Lactone from Helenium microcephalum," J. Pharm. Sci., 65 (9) 1411 (1976). K. H. Lee, Y. Imakura, and H. C. Huang, "Antitumor Agents 24. Bruceoside-A, a Novel Antileukemic Quassinoid Glycoside from Brucea javanica," J. Chem. Soc. - Chem. Comm., 69 (1977).